In the H.264 standard (see Non-Patent Literature 1), image (including video) coding typically comprises intra coding using spatial prediction methods, and inter coding using temporal prediction methods.
Temporal prediction may be performed for a number of different inter-coding block types, such as Inter 16×16, Inter 16×8, Inter 8×16, inter 8×8, inter 8×4, inter 4×8 and Inter 4×4, while spatial prediction may be performed for a number of intra-coding block types, such as Intra 16×16, Intra 8×8 and Intra 4×4. Intra Pulse Code Modulation (IPCM) blocks are one kind of intra coding blocks.
IPCM blocks are blocks of uncompressed image samples where raw luma and chroma samples are signaled in the coded stream. They are typically used in the case when the entropy coder produces more bits compared to raw data bits when coding a block of image samples. In general, IPCM blocks are coded as uncompressed data in the coded stream.